To use opDispatch

[bearophile]

BCS:

> I guess I didn't rememeber correctly. Anyway, this work:
> 
> 
> import std.stdio;
> 
> template If(bool b, T, F) { static if(b) alias T If; else alias F If; }
> 
> struct S
> {
>    int[string] vals;
>    template opDispatch(string s)
>    {
>    If!(T.length == 1, void, int) opDispatch(T...)(T t)
>    {
>       static if(T.length == 1) vals[s] = t[0];
>       else return vals[s];
>    }
>    }
> }
> 
> void main()
> {
>   S s;
>   s.foo = 5;
>   writef("%s\n", s.foo());
> }

It works :-) In my alternative implementations I have never put that () after the new method name.
Using @property here doesn't work.
I have modified (hopefully improved) your version like this:


import std.stdio: writeln;
import std.traits: isImplicitlyConvertible;

struct S(T) {
    T[string] data;

    template opDispatch(string name) {
        @property T opDispatch(Types...)(Types args)
            if (!args.length || (args.length == 1 && isImplicitlyConvertible!(Types[0],T))) {
            static if (args.length) {
                data[name] = args[0];
                return args[0];
            } else
                return data[name];
       }
   }
}

void main() {
    S!long s;
    s.foo = 5;
    // writeln(s.foo); // err
    writeln(s.foo());
}


Bye,
bearophile